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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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    <script>
        // undefined
        // var x;
        // alert(x)
        // 字符
      var str1 ="hello world"
      var str2 ="hello world"
      console.log(str1)
      console.log(str2)
    //   var str3 ="hello world";
      var str4 ='小明说"我觉得小红很漂亮"'
      console.log(str4)
      var str ="Java";
    //   JS中先运算等号右边的语句
    str = str + "script";//字符串中+号是连接的意思 JavaScript
    console.log(str)
    </script>
</body>
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